So far as I know Meyer has RIR, but it seems like sometimes they or the feed stores will just sell a mix of all of the red colored breeds as "production reds". PRs should work fine in a black sex link cross. Not sure if you have seen it, but this was a nice thread on sl's https://www.backyardchickens.com/t/261208/sex-linked-information

You should get what they call RIR .... RIR are one of those breeds though where there seems to be a big difference between hatchery quality RIR and heritage RIR or breeder/show bred RIR bred more to the standard.

I have not been impressed with the quality standard of hatchery chicks so far in my latest chicken venture. I am going to start searching for more reputable places to get my stock even if it does cost a little more. The one hatchery whos rir I want to try is central hatchery in Nebraska. Their rir look better in their pics and they say they get their breeding stock from a good looking line which hasn't been bred down. But their minimum order is quite large.